1. Field of the Invention
The present invention relates to seat-bed assemblies, and, more particularly, to seat-bed assemblies mounted in a motor vehicle.
2. Description of the Related Art
Seat-bed assemblies having a seat support and a back support which may be moved from a seat position to a bed position are known in the art. For example, my earlier U.S. Pat. Nos. 4,321,716 and 4,563,784, disclose manually operated and power actuated seat-bed assemblies, respectively. With such known devices a horizontal support extends between upright support members. The horizontal support comprises a plate-like structure and includes a pair of guide channels comprising slots cut into the horizontal support. A linkage structure includes a first link which interconnects one of the guide channels with a seat support, and a second link which interconnects the other of the guide channels with a back support. To connect the first and second links with the respective guide channels, a pair of pins or the like extends through each respective guide channel and an opening formed in each of the first and second links. The first and second links are thus disposed adjacent to the guide channels and along one side of the horizontal support.
Although a step forward in the art, a problem with such designs is that when a forward or rearward force is applied to the back support (and thus the linkage structure interconnecting the horizontal support with the back support), a twisting moment is exerted on the link at the point of connection to the guide channel because the link is disposed to the side of the horizontal support. Such twisting may in turn cause bending or bowing of the link which results in a decreased ability to withstand the forward or rearward force. Additionally, the shear force applied to the pin interconnecting the link and guide channel is relatively high because the pin is only connected to the guide channel at one location.
Another problem is that the linkage structure, seat support and especially the back support may be movable relative to each other in a sideways direction.
A still further problem is that the cushions overlying the seat support and back support interfere with each other when the seat-bed assembly is moved from the seat position to the bed position, or vice versa. To wit, when the seat-bed assembly is in the seat position, it is desirable to have the cushions overlying the seat support and the back support disposed closely adjacent to each other. However, with known structures, the guide channels comprise straight slots formed in the horizontal support. When the seat begins movement from the seat position to the bed position, the rear edge of the seat support travels in an upward and forward direction, while the bottom edge of the back support travels in a downward and forward direction. The movement of the seat support in an upwards direction and the back support in a downwards direction causes the seat cushion and back cushion to contact and interfere with each other. Such interference makes movement from the seat position to the bed position more difficult. A similar problem occurs when the seat-bed assembly is moved from the bed to the seat position.
Yet another problem is that the linkage structure may contact and thereby damage upholstery or surfaces of the seat-bed assembly. For example, a link may extend through a front surface of the seat-bed assembly. However, for aesthetic purposes, it may be desirable to attach an upholstered panel to the front surface of the seat-bed assembly. If the link extends through the front surface of the seat-bed assembly, it may be necessary to cut through the upholstered panel to allow the link to extend therethrough. The opening decreases the aesthetic appeal of the seat-bed assembly, and adds to the cost.
A further problem is that with conventional designs, the back support directly engages the frame when the seat-bed assembly is in the bed position. Since the back support is usually upholstered on the back surface as well as the front surface thereof, the upholstery engaging the frame may become worn and damaged.